1989 Fiscal Year Final Research Report Summary
Studies on the Application of the Angular Overlap Model of the Ligand Field
| Project/Area Number |
63540496
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
無機・錯塩・放射化学
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| Research Institution | Daido Institute of Technology |
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Principal Investigator |
YAMATERA Hideo Daido Instituteof Technology, Department of Chemistry, Professor, 工学部, 教授 (70022499)
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| Project Period (FY) |
1988 – 1989
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| Keywords | angular overlap model / ligand field / X-ray absorption spectrum / XANES / tetrachlorocuprate(II) / 8-coordinate complex / coordination structure / bond number |
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| Research Abstract |
The angular overlap model (AOM) of ligand field was applied to the following subjects and was shown to be useful. Development was attained in the formulation and application of the AOM. 1. Description of the ligand field of a symmetrical pi-conjugated bidentate ligand (Joint research with C.E. Schaffer): Introduction of radial parameters of molecular (instead of atomic) character for ligands of such kind enabled them to be treated by the AOM as originally formulated, without introducing an extra term as proposed by Ceulemans et al.
2. Correlation between the intensity of the 1s->3d X-ray absorption (in XANES) by [CuCl_4]^<2-> -containing compounds and the geometrical structure of [CuCl_4]^<2->: The experimental finding that the intensity of the 1s->3d absorption increases with the increase in the dihedral angle between two Cl-Cu-Cl planes of [CuCl_4]^<2-> was related to the mixing of d_<xy> and p_z orbital which increases with increasing dihedral angle.
3. Geometrical structure of 8-coordinate complexes: In contrast to the tendency as seen in inorganic-chemistry textbooks that repulsion between valence-shell electron pairs is the main factor controlling the arrangement of ligands, formation of stronger metal-ligand bonds is considered to be a mole important. The angular overlap integral of each central-atom orbital with ligand sigma orbitals was taken as a measure of bond number. As the sigma bond number cannot exceed one per orbital, values exceeding one were regarded as one (in some cases, as smaller than one) and their sum over the central-ion orbitals is named as "effective bond number" (EBN) of the complex. The largest EBN is 7 for the cubic arrangement of ligands and -7.5 for tetragonal antiprism and triangulated dodecahedron. The EBN is not very sensitive to the change in ligand positions, in agreement with appreciable differences in shape between compounds. All known compounds lies in the region of EBN<greater than or si
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